Apparatus for filtering slimes.



0. BUTTERS. APPARATUS FOR FILTBRING SLIMES. APPLICATION FILED JUNEll,1913. 1,100,219. Patented June 16,1914.

. 3 SHEETS-SHEET 1.

WITNESSES lNl/E/V TOR W 4 V M I %XA MA ATTORzV-Q G. BUTTERS. APPARATUSFOR FILTERING SLIMES. APPLICATION FILED JUNE 11, 1913.

1,100,219, Patented June 16,1914.

2' SHEETS-SHBET 2.

lT/V 885$.- a lwmron,

W W M I ATTOR r$ UNITED STATES PATENT OFFICE.

CHARLES TBUTTERS, OF OAKLAND, CALIFORNIA;

APPARATUS FOR FILTERING SLIMES.

T all whom. it may concern.

Be it known that I, CHARLES Burrnns, a

A citizen of; the United States, and a resident of Oakland, county ofAlameda, State of California, have invented certain new and usefulImprovements in Apparatus for Filtering Slimes, of which the followingis a speci cation.

The object of my invention is to shorten the time taken for a cycle ofoperation in the process of filtering valuable compounds, such asslimes, which result from the well known cyanid process of treatingores.

Another object of my invention is to lower the .costof filter leaveswhile at the same time increasing their life and value.

In abstracting the values from slimes one of the most difficult andtroublesome problems is to dislodge reliably and within an economicaltime, the slime cake from the surface of the filter medium after thefilter process has been completed, without injuring the filter surfaceof the leaf.

It has been the practice heretofore to dislodge slime cakes by airpressure placed on the interior of the leaves while suspended in theair, or this has been accomplished in some cases by water under pressurebeing passed through the filter medium in a direction reverse to that ofthe filtrate. It has been supposed heretofore that to dislodge the cakereliably and within an economical time, pressure was necessary whetherof air, water or other fluid in the dislodging step, and specialprecaution has sometimes been taken to get a uniformly thick, cohesiveand resistant cake deposit such that the fluid under pressure mightdislodge it as an entirety and make it unnecessary to use additionalmeans to dislodge the cake completely. By my process such uniformity ofthe cake is of no importance at all to the cake dislodgment, andconsequently the filtering operation may be more economical.

If notable internal pressure is put on a leaf forcake-dislodgmentpurposes, a heavy filter medium is necessary and meansmust be provided to prevent distention or ballooning of the filtermedium. Various means have been devised to this end, all of which haveadded to the difliculty of cake-dislodgment. As a matter of practice,too, it is found that all such means are a hindrancr to proper andeconomical operation; further, they shorten the life of the leaves, butthey have been regarded as indispensable Specification of LettersPatent.

Patented June 16, 1914.

Application filed June 11, 1913. Serial No. 772,946.

tively large holes are made in the media.

Also, these holes make the media more liable to rupture under internalpressure, thus shortening their life.

I have discovered that pressure is unnecessary to reliablecake-dislodgment within an economical time, and that complete successcan be attained by saturation of the entire area of the filter medium.It is found in practice that these cakes have unusual adhesion andcohesion, and that when a cake is formed on each side of a filter leafthey are not easily dislodged. Due to the great cohesion of the cake itis very important that the upper part, as well as the other parts, ofthe filter medium be saturated in the dislodging step, as it is foundthat the adhesion of the cake to the med um is reatly lessened, and thatthe time for dislodgment is materially shortened thereby. This has notbeen attained in leaves heretofore constructed because they containedenough air to prevent water reaching the top part thereof even whenadmitted under pressure. This was true in spite of the fact that theleaf might be under vacuous conditions at the time the water was firstadmitted.

The cake to be dislodged from a filter medium adheres more closely tothe surface of the filter medium if there is any excess of external overinternal pressure. It is, therefore, desirable to have the internal andexternal pressures equalized during the dislodging step, and I havedevised means to that end, which equalize such pressures by allowingcommunication between the external and the internal water. A leaf whichembodies my invention cannot have internal pressure during thedislodging step. But such pressure is not necessary, however, since bymy inven: tion the cake can be dislodged without it. It is understoodthat the cake is dislodged while the leaf is submerged in wash water.This means that there will be considerable hydrostatic pressure on theoutside of the leaf. It has been found by experiment that the differencein specific gravity of the more l pump 10 through end members 16,members or less dirty tank wash water and the relatively cleancake-dislodging water would be sufiicient to maintain acolumn of therelatively clean water inside the leaf several inches higher than thelevel of the tank wash water so that the relief valve and the inlet forthe cake-dislodging water may be several inches above the surface of thetank wash water without producing greater pressure inside the leaf thanthe outside pressure on the leaf. The above fact is useful in practiceas it gives considerable latitude between the level of the tank washwater and that of the entrance to the relief valve and that of thefunnel valve through which the dislodging water is supplied to the leaf,thus preventing the entrance of the tank wash water into the leaf, whileat the same time preventing excess of internal pressure.

The above facts make it possible in my type of leaf to completelysaturate the entire filter surfaces during the dislodging step becausethe air is permitted to escape through the relief valve. Also, as thereis never any internal pressure a lighter filter cloth may be employedand all means heretofore required to prevent ballooning dispensed with.Therefore, the filter surfaces may be smooth, being clear of all mannerof bracing, stitching or other surface-roughening means which haveheretofore been necessary to prevent ballooning when other practicablemethods of cake-dislodgment have been used, and consequently the cake ismore easily dislodged.

Other advantages will be apparent. from the following detaileddescription taken in connection with the accompanying drawings, inwhich- Figure 1 shows a diagrammatic plan view of a general layoutshowing a clean water source and piping for supplying the water to theleaves; Fig. 2 is a side elevation of the devices shown in Fig. 1; Fig.3 is a plan of a portion of a vat with several leaves therein; Fig. 4 isa view of a leaf embodying my invention; Fig. 5 is a plan view of arelief valve; and Fig. 6 is a section of a relief valve.

In Fig. 1 are shown a plurality of vats 1 in which the leaves 2 areplaced as shown in Fig. 3. These leaves are connected with the cleanwater source 3 by means of piping 4, risers 7, pipe 5, pipes 32, andfunnel 30 on one side, and by means of the pipe 37, pipes 32 and funnels35 on the other side. In each case the pipes 32 may discharge intofunnels, or other suitable means for conducting water into the leaves.may reach all the leaves quickly the pipe 5 is arranged along the top ofthe vats, and is connected with the pipe 4 from tliewater supply 3by'means of risers 7 Tlfe interior of the leaves is connected with'tlteva'cunm- In order that the water (J, sightlasses 38, valve members39 and pipe The pipes 4, 5 and 33 are suitably supported by any means,such as members 34 fastened to the side of the vat. The pipe 37 may besupported by similar means. In pipe 4 is placed valve 8 so that thewater may be admitted to, or cut off from, the leaves. In the pipe 37 isthe valve 40 by which the admission of water into the pipe 37, andtherethrough into the leaves through funnels 35, mav be controlled ashereinafter explained. The pump 10 is shown connected with the pipe 33for the purpose of creating a vacuum within the leaves when desired.\Vhen it is desired to begin the filtering operation the valves 8 and 40are closed, the valve 9 is opened and the pump 10 started to decreasethe pressure within the filter leaves, and thereby draw a filtaatethrough and form cakes on the surface of the filter media 19. \Vhencakes of sufiicient thickness have been formed, they may be -.treated inwell known ways with barren sofilling the leaves, saturating the filtermedia and thereby causing the cakes to drop within four or five minutes.The valve members 31 will have been removed from the funnels to allowthe entrance of water into the leaves, or they may be made of lightmaterial such as wood, in which case they will automatically open toallow water to enter and will be in position again when vacuum isapplied. The thick slime is then run out from the bottom of the vatsinto therunway 12, and thence to the slime-pit. The vats may be properlysupported by any convenient means such as the pillars 13 and I-beams 14,as shown in Fig. 4.

The valves may be of the type shown in Figs. 5 and 6, or they may befunnelvalves, as shown in other figures of the drawing, preferably thelatter, for reasons given hereinafter.

As shown in Fig. 4, the leaf comprises a frame having members 15, 16, 17and 18, preferably of tubing. secured a filter medium 19 of canvas orother suitable material. Inside the filter-leaf is a fibrous filler 20preferably of cocoa mat, for holding the sides thereof apart when vacuumis .created within the leaf. This filler may be supported by anysuitable means, as for instance, from the top frame member 18. The lowerframe member 15 is perforated or slotted along its upper side and isconnected to a vacuum pump 10, or other pressure-decreasing meansthrough the right- Over this frame,is

hand end member 16 and the connection 6,

which may be of rubber, or other suitable material, sight-glass 38,valve member 39 and the pipe 33. The filtrate is removed by means of thepump 10. The left-hand frame member 17 is plugged by any suitable meanssuch as a wooden plug, as shown at 21 in Fig. 4E. The top frame member18 is perforated or slotted along its lower side and to this member isattached a suitable relief valve 35. This member is also It is usefuladmitting water from the tank 3 through avalve 40, pipe 37, pipes 32into the funnels 35,

and for this purpose the relief valve may be provided with a funnel. Atthe time that the water is admitted the valve member,

such as a ball 36, is removed from .the funnel. It is not necessary thatthe relief valve be connected to the frame member, but this arrangement.is preferred and it is so illustrated in the drawings. The pipe 22 cornecting the valve to the leaf may be of any suitable length. The reliefvalve should be connected to the upper portion of the leaf in order toallow the escape of air.

' Valvesll are attached to the lower frame member of the leaf. Thesevalve as will be seen are inverted. They are shozn in detail in Figs. 5and 6. Their function is to open when the internal pressure has substantially equaled the external pressure, and thereby open freecommunication between the exterior and interior of the leaf, whereby thehydrostatic pressures on the sides of the filter surfaces will beequalized. These valves may be connected to any submerged portion of theleaf, but they are preferably connected. as shown in the drawing. Asshown in Fig. 4 the leaf is provided with a funnel valve at each uppercorner. Vhile The function of the valve at the right-hand corner is toadmit water without pressure into the leaf for the purpose of dislodgingthe cake as here- 'toforedescribed. The functions of the funnel valve atth'e left-hand corner are to allow water to be run through the leaf for00- casionally washing out the cocoa mat, or other filler, after thecake has been dislodged, and to permit air to escape while the leaf isbeing. filled with water from the funnel at the opposite corner duringthe cakedislodging step. The funnel valves at .the

right-hand corners of the leaves may be dispehsed with and water fordislodging the cakes supplied through the members 6, if desired. Therecan be no internal pressure under these circumstances due to thepresence of the valves 11 at the bottom of the leaves and the reliefvalves at the top thereof. Vate'r may be run through the funnels 35, andconsequently through the leaves and out at the valves 11 while the vatis beingfilled with slime to submerge the leaves for the purpose ofavoiding the entrance of slimes into the leaves at that time. At thistime the balls 36 will be removed from the .funnels to permit the waterto run through the leaf.

The preferred form of pressure-equalizing valve is shown in detail inFigs. 5 and 6, but other kindsof valve may be used at the lower cornersof the leaves provided it will allow communication between the externaland internal water when the internal pressure nearly equals the externalpressure. The valve hereafter described is byway of example only andmust not be considered as liaiiting my invention. As shown in Figs. 5and 6 the valve consists of a pipe-coupling 23around which is securelyclamped n rubber tube 24L the upper end of which acts v as a valve seat.the coupling 23 by :a band 25 in any well known. manner. Arranged tocooperate with the seat- 24 is a ball 26 of 'rubber g For. the purposeof confining the movement of.

This tube'is clamped around the ball. guards 27 are placed aroundgsaine,

as clearly shown in the drawing. The function of this valve whenconnected to-a sphmerged portion of the leaf is to establishcommunication bet-ween the water 'i-nsidez the time that the internalhydrostatic pressure nearly .equals the external hydrostatic pressure,so that these pressures will be "equalized and kept equalizedso long asthe valve remains open. closes if the external pressure becomes greaterthan the internal pressure, and this prevents entrance thereafter ofexternal water into the leaf.

The operation of my device is as follows: I i

The leaf is completely submerged in the slimes bath, care being takennot to allow slimes to enter the funnel valves. To pre vent slimesentering the leaf through the valves 11 before the vacuum is turned on,water may be run through the leaf at. that time by admitting it throughthe funnels and allowing it to discharge through the valves 11. Afterthe leaves aresubmerged a few inches the water supply through thefunnels 35 is cut oil. the balls placed therein, and suction applied tothe interior-of the leaf by any means such as a vacuum pump 10. As soonas the vacuum is turned on. the valves 11, as well as the valves 30and35, will close and seal. The filtrate is carried off by thepressure-decreasing means aid the suction is continued until a cake ofproper thickness is deposited on the filter surface. This cake may thenbe variously treated with barren solution and wash This valveautomatically .leaf and the water outside the leaf at-Tthe water, thevalves 11, 30 and 35 remaining sealed throughout these operations. Inorder' to dislodge the cakes, the filter leaves being submerged, in'washwater, the vacuum is turned off, the balls 31 are removed and internalwater thereby equalizing the external and internal pressures, and thecakes will then berapidly dislodged. The filter leaf may then bewashed'out internally by admitting water through the funnel valves 35 atthe left-hand corner and allow. ing it to discharge through the" valves11 at the lower corners.

Various changes may be made in my apparatus and still fall within thescope of the invention. I

Having described my invention, what I claim as new and desire to'secureby Letters Patent, is

1. g A filter leaf having means for equalizing the external and internal'water pressure thereon while said leaf is'submerged.

2. A filter leaf having submerged pressure equalizing means connectedtherewith.

3. A filter leaf having automatic hydrostatic pressure equalizing meansconnected thereto.

4. A filter leaf having a submerged pressure equalizing valve connectedthereto.

5. A filter leaf having a submerged automatic pressure equalizing valveconnected thereto.

6. A filter leaf having a hydrostatic pressure equalizing valveconnected with a submerged portion thereof.

7. A filter leaf having an automatic hy drostatie pressure equalizingvalve connected with a submerged portion thereof.

8. In a filter leaf the combination of a frame structure, filter mediacarried there by, an open water pipe connected to the upper portion ofsaid leaf and a submerged pressure equalizing valve connected with .saidleaf. p

9-.In a filter leaf the combination of .means for admitting waterwithout pressure-to the interior thereof and means for allowingcommunication between external sure to the interior of the leaf, meansfor allowing communication between the extenor and interior water of theleaf when the leaf is submerged and means for allow 'ing the escape ofair from the leaf.

11. In a filter leaf the combination of a funnel for admit-ting water tothe leaf, means for supplying water to the funnel,

a valve for allowing communication of the exterior water and interiorwater of the leaf when it is submerged and a relief valve for allowingthe escape of airfrom said leaf.

12. A filter leaf comprising a frame, a filter medium mounted on eachside of said frame, means for separating the sides of the filter medium,and means adapted to equalize the water pressure between the insideandoutside of said leaf."

13. In a suction filter leaf, the combination of a frame, filter mediacarried by said frame, and a valve connected with an immersed portionof. said leaf forequalizing the internal and external water pressurethereof.

14. In a suction filter leaf, the combination of a frame, filter mediacarried by said. frame, and a valve connected with an immersed portionof said leaf to prevent an excess of internal water pressure'therein.

15; In a suction filter'leaf, the combinationof a frame, filter mediacarried by said frame, an air valve connected with the upper portion ofsaid'leaf, and a valve for equalizing the internal and externalhydrostatic pressure of said leaf connected to the lower portionthereof.

16. In a filter leaf the combination of means for admit-ting water tothe leaf withoutpressure, means for equalizing hydrostatic pressures onthe leaf, and means for running water through the leaf to wash theinterior thereof.

17. In a filter leaf, the combination of a header, a frame, a filtermedium surrounding said frame and having'a plurality of openings in itsbottom side adapted to be closed byflsuction, and a porous filler between the sides of said medium.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses. n p

CHARLES BUTTERS.

VVit-nesses: a

NEWTON A. BURGESS, EDWIN SEGER.

